This invention relates to an adjustable lumbar support for chairs and vehicle seats, which provide an adjustable contour to the seat back for varying degrees of lumbar support to the seat occupant.
Commercially produced chairs and vehicle seats with fixed back supports do not provide adequate lumbar support for many users. Adjustable lumbar supports have been developed to improve the comfort of conventional seats. Adjustable lumbar supports are mechanical devices built into the seat frame that extend and retract within the frame to alter the contour of the lumbar region of the seat back. Typically, adjustable lumbar supports are actuated by a Bowden cable, which is controlled by a mechanical regulator or some other electronic control device that is readily accessible to the seat occupant. Conventional adjustable lumbar supports are heavy and complicated mechanical devices, that must be specifically designed for installation with the internal frames of the particular chairs and vehicle seating. Most lumbar supports employ either a linkage (scissor) type actuation mechanism or an arching type actuation mechanism.
U.S. Pat. Nos. 5,553,919; 4,564,235; 4,657,304; 4,313,637; 4,295,681; and 4,182,533 describe typical lumbar supports, which employ linkage or scissor type actuation mechanism. These lumbar supports include a lumbar plate, which is moved up and down against the seat back by the actuation of a linkage mechanism of scissored or lever arms. The range of lumbar adjustability is limited by the amount of travel afforded by the length of the lever arms of the linkage mechanism. Decreasing the size of the lumbar support often reduces the range of lumbar adjustability. Increasing the travel of the linkage mechanism means increasing the size and weight of the lumbar support, which leads to increased material costs and space required for installation within the seat back. In addition, increasing the size of the linkage mechanism also increase the amount of pulling force from the Bowden cables needed to actuate the lumbar support. The length, weight and complexity of the linkage mechanism all add to the inertial force or load, which the Bowden cable must over come in order to actuate the mechanism.
U.S. Pat. Nos. 6,254,187; 6,003,941; 5,775,773; 5,626,390; 5,498,063; 5,462,335; 5,397,164; and 5,050,930 describe typical lumbar supports, which employ an arching type actuation mechanism. These lumbar supports include one or more resilient bands that are bowed against the seat back to various degrees to adjust the contour of the seat back. The resilient bands are bowed by mechanisms connected to the Bowden cable. In an arching type lumbar support, the bowing of the bands creates an inherent spring tension in the actuation mechanism. Consequently, additional force must be applied to the Bowden cable to just over come the inherent load or spring tension in the mechanism itself.
As described, both linkage and arching type lumbar supports have several practical drawbacks. It continues to be desirable to have small light weight modular lumbar supports, which require minimal force to actuate. It is particularly desirable to have a lumbar support whose actuation mechanism has little or no inherent load, which must be over come by the Bowden cable or adjustment controls.
The adjustable lumbar support of this invention is a small light weight modular device that requires minimal force to actuate. The lumbar support employs a linkage mechanism that has little or no inherent load, which must be over come by the Bowden cable or adjustment controls. The lumbar support includes a mounting base, a lumbar plate, and a pair of articulated linkage arms. Each linkage arms includes an upper and lower segment, which are pivotally connected by an elbow joint. The lower segments are pivotally connected to the mounting base and the upper segments are pivotally connected to the lumbar plate. A Bowden cable is connected to the linkage arms at the elbow joints, such that extending or retracting the cable pulls or pushes the elbow joints together or apart to actuate the lumbar support. The linkage mechanism composed of the linkage arms and the six pivotal joints allows the lumbar plate a limited degree of pivotal movement between its fully extended and fully retracted positions. This xe2x80x9cfloatingxe2x80x9d action creates a self adjustment mechanism, which ensures that the lumbar plate remains parallel to the seat back even as a seat occupant shifts in the seat. Each of these components is constructed of composite materials, such as a strong fiberglass reinforced thermoplastic, which reduces the weight of the device while providing sufficient structural strength and integrity. Furthermore, the plastic construction provides resilience and the ability to form the components so that they can be assembled by snap fit interlocking connection, thereby eliminating fasteners and other linkage components.
Accordingly, an advantage of the lumbar support of this invention is that it provides a small light weight modular device, which can be easily incorporated into conventional chair and vehicle seat designs.
Another advantage of this invention is that the lumbar support allows the lumbar plate to pivot or xe2x80x9cfloatxe2x80x9d independently of the linkage mechanism between its fully extended and fully retracted positions.
Another advantage of this invention is that the linkage mechanism of the lumbar support exerts little or no inherent load or inertia on the Bowden cable or actuation controls.
Another advantage of this invention is that the components of the lumbar support are constructed from composites or plastics so as to reduce the weight and the complexity of the device.
Other advantages will become apparent upon a reading of the following description.